The sport of aggressive in-line skating has become increasingly popular. Aggressive in-line skates include an upper boot and a lower base that is ruggedly constructed. A plurality of wheels are rotatably secured between first and second opposing frame rails to the lower side of the base. The frame rails are either integrally formed with the base, such as by molding, or a frame may be bolted, riveted, or otherwise secured to the base. The base is conventionally molded or assembled from rigid thermoplastic polymers.
The base of an in-line skate defines flat longitudinal surfaces on either side of the frame rails. During aggressive skating maneuvers, a skater may position the base of the in-line skates to contact and slide along stair railings, curbs, ramps, benches or other longitudinal surfaces. This sliding maneuver is referred to as "grinding". The wheels of the in-line skate do not roll along the surfaces as in conventional skating, but rather the flat longitudinal surfaces on either side of the frame directly contact and ride along the wheel, curb, ramp, etc. The skater's weight is directly transmitted through the base to the longitudinal surface on which the skater is grinding, and the skater must carefully control the position of the skate relative to the longitudinal surface to maintain balance.
As the skater slides along the longitudinal surface, significant frictional forces develop between the base of the skate and the longitudinal surface. Over time, this results in substantial wear of the base, scoring deep grooves in the base that ultimately destroy the integrity of the skate. The high strength, rigid plastic materials usually used in the base are not very resistant to wear. The useful life of aggressive skates is significantly limited by this wear and abrasion. Additionally, the skate base should preferably be free to slide smoothly on a longitudinal surface, so as to avoid binding and loss of balance. A worn skate base may bind or seize when a skater attempts to slide or "grind" along a surface, due to the development of excess friction.